Methods and uses for controlling sludge in engines

ABSTRACT

The use as a sludge controlling additive in a fuel composition for a spark-ignition internal combustion engine or a compression-ignition gasoline internal combustion engine of a combination of: a. a hydrocarbyl-substituted aromatic compound; and b. a polyalkylene amine. The fuel composition may also be used for maintaining oil pathways and/or lubrication in an engine.

This invention relates to methods and uses and in particular aspects toa method of controlling sludge formation in a spark-ignition internalcombustion engine or a compression-ignition gasoline internal combustionengine, and in other aspects to the use of a combination of additives asa sludge controlling additive in a fuel composition for a spark-ignitioninternal combustion engine. The invention also relates to methods formaintaining oil pathways and lubrication in an engine.

During operation of a spark-ignition internal combustion engine, thecrankcase lubricant oil can become diluted with fuel, water and/orcoolant. The lubricant oil can also become contaminated with chemicalspecies which can accelerate lubricant oil oxidation. Examples of thesechemical species include wear metals and oxidative non-metallicsubstances which can enter the crankcase through blow-by. The lubricantoil is also subject to high temperatures. As a result of these chemicaland physical conditions, oxidation, polymerisation and agglomeration ofthe lubricant oil may occur, creating a highly viscous tar-like materialknown as sludge from the degraded oil. The sludge may also incorporatespecies derived from fuel, water, coolant, soot and wear metals. Sludgecan build up on many components of the engine, including the rockercover(s), the camshaft baffle, the timing chain cover, the oil pan andits baffle, the oil screen and the valve deck area.

Sludge can reduce the performance of an engine. For instance, enginesludge can be a factor in compromised oil pathways and enginelubrication. This can lead to engine failure.

Typically, formation of sludge has been controlled using additives inlubricating oils. According to the abstract of U.S. Pat. No. 3,784,474,a lubricating oil containing a hydrocarbyl-substituted amine ashlessdetergent, a polyoxyalkylene derivative and an alkaline earth metalreduces or prevents the formation of varnish, sludge and deposits on theinner metallic surfaces of internal combustion engines.

However, there remains a need for a fuel composition comprisingcomponents which provides suitable detergency to a spark-ignitioninternal combustion engine, yet controls the formation of sludge.

According to its paragraph [0145], US2013/000584 discloses a fuelcomposition comprising one or more poly(hydroxycarboxylic acid)derivatives having a terminal amine group for inhibiting the formationof sludge. The detergency of the fuel composition is not disclosed inUS2013/000584.

According to its paragraph [0002], US2006/0277820 relates to a depositcontrol additive composition for a fuel comprising polyisobutylene amine(PIBA) having an average molecular weight of about 700 to about 1000 anda Mannich Base as synergistic components of the deposit control additiveformulation.

Paragraph [0015] of US 2006/0277820 states:

-   -   “Mannich bases have been used in isolation or in combination        with diamine to reduce deposits on carburet[t]or surfaces. As        disclosed in the present application, a surprising result has        been achieved by using a Mannich base and Polyisobutylene amine        as synergistic components of a deposit control additive        formulation to drastically reduce deposits on carburet[t]or and        keep port fuel injectors and intake valves clean in gasoline        fuel[l]ed spark ignition internal combustion engines.”

Paragraph [0069] of US2006/0277820 relates to an Inlet Valve DepositTest using Mercedes Benz M111 Engine as per CEC F-20-A-98 and paragraph[0070] relates to Port Fuel Injector Fouling Bench Test. The formationof sludge is not addressed by the disclosure in US2006/0277820.

Therefore, there remains a need for methods and uses aspects of whichreduce or at least mitigate problems, for example as identified above.

According to a first aspect of the present invention there is provided amethod of controlling sludge formation in a spark-ignition internalcombustion engine or a compression-ignition gasoline internal combustionengine which method comprises supplying to the engine a fuel compositionwhich comprises a combination of:

a. a hydrocarbyl-substituted aromatic compound; and

b. a polyalkylene amine.

According to a further aspect of the present invention there is providedthe use as a sludge controlling additive in a fuel composition for aspark-ignition internal combustion engine or a compression-ignitiongasoline internal combustion engine of:

a. a hydrocarbyl-substituted aromatic compound; and

b. a polyalkylene amine.

According to a further aspect of the present invention there is provideda method of reducing the sludge forming tendency of a fuel compositionfor use in a spark-ignition internal combustion engine or acompression-ignition gasoline internal combustion engine which methodcomprises incorporating into the fuel composition in one or more steps:

a. a hydrocarbyl-substituted aromatic compound; and

b. a polyalkylene amine

to produce a fuel composition which comprises said additives incombination and which on use in said engine produces less sludge thanthe sludge formed when using in said engine the fuel composition withoutsaid combination of additives.

According to another aspect of the present invention there is providedthe use of an additive composition comprising a combination of:

a. a hydrocarbyl-substituted aromatic compound; and

b. a polyalkylene amine

for improving the sludge control performance of a fuel composition in aspark-ignition internal combustion engine or a compression-ignitiongasoline internal combustion engine.

According to another aspect of the present invention there is provided amethod of maintaining oil pathways and/or lubrication in aspark-ignition internal combustion engine or a compression-ignitiongasoline internal combustion engine which method comprises supplying tothe engine a fuel composition which comprises a combination of:

a. a hydrocarbyl-substituted aromatic compound; and

b. a polyalkylene amine.

According to another aspect of the present invention there is providedthe use as an oil pathway and/or lubrication maintaining additive in afuel composition for a spark-ignition internal combustion engine or acompression-ignition gasoline internal combustion engine of:

a. a hydrocarbyl-substituted aromatic compound; and

b. a polyalkylene amine.

In embodiments, the hydrocarbyl-substituted aromatic compound is aMannich base additive. In embodiments, the polyalkylene amine is apolyisobutylene amine.

Aspects of the present invention address the technical problemsidentified and others, by the use in combination of ahydrocarbyl-substituted aromatic compound and a polyalkylene amine.

In particular it has been found that a fuel composition comprising acombination of a hydrocarbyl-substituted aromatic compound and apolyalkylene amine exhibits beneficial sludge formation control whenused in a spark-ignition internal combustion engine.

Polyalkylene Amine.

The polyalkylene amine may be a poly C₁₋₁₀-alkylene amine. For instance,the polyalkylene amine may be polyethylene amine, a polypropylene amine,a polybutylene amine, a polypentylene amine or a polyhexylene amine. Inexamples, the polyalkylene amine is a polybutylene amine, in particulara polyisobutylene amine.

Polyisobutylene amines are also sometimes called polyisobutylamine orPIBA. Examples of suitable polyisobutylene amines include mono-amines,di-amines and polyamines of polyisobutylene including for example,polyisobutylene that is a homopolymer of isobutylene and polyisobutylenethat is a polymer of isobutylene with minor amounts (for example up to20% by weight), of one or more other monomers including for examplen-butene, propene and mixtures thereof.

Examples of suitable polyisobutylene amines include polyisobutyleneamines disclosed in, and/or obtained or obtainable by methods describedin, U.S. Pat. No. 4,832,702, U.S. Pat. No. 6,140,541, U.S. Pat. No.6,909,018 and/or U.S. Pat. No. 7,753,970.

Examples of suitable polyisobutylene amines include polyisobutyleneamines disclosed in, and/or obtained or obtainable by methods describedin, U.S. Pat. No. 4,832,702. Thus, suitable polyisobutylene aminesinclude compounds represented by the structural formula I:

in which R₁ is a polybutyl- or polyisobutyl group derivable or derivedfrom isobutene and up to 20% by weight of n-butene and

-   R₂ and R₃ are identical or different and are each independently:    -   hydrogen;    -   an aliphatic or aromatic hydrocarbyl group;    -   a primary or secondary, aromatic or aliphatic aminoalkylene        group or    -   polyaminoalkylene group;    -   a polyoxyalkylene group;    -   a heteroaryl or heterocyclyl group; or    -   together with the nitrogen atom to which they are bonded form a        ring in which further hetero atoms may be present.

In at least some examples, R₂ and R₃ are identical or different and areeach independently:

-   hydrogen;-   alkyl;-   aryl;-   hydroxyalkyl; or-   an aminoalkylene group represented by the general formula (II):

-   -   wherein R₄ is alkylene and R₅ and R₆ are identical or different        and are each independently: hydrogen; alkyl; aryl; hydroxyalkyl;        polybutyl; or polyisobutyl; or

-   a polyaminoalkylene group represented by the general formula (III):

[—R₄—NR₅]_(m)R₆   (III)

-   -   wherein the R₄ groups are the same or different and the R₅        groups are the same or different and R₄, R₅ and R₆ have the        above meaning and m is an integer from 2 to 8; or

-   a polyoxyalkylene group represented by the general formula (IV):

[—R₄—O—]_(n)X   (IV)

-   -   wherein the R₄ groups are the same or different and have the        above meaning, X is alkyl or H and n is an integer from 1 to 30.

In at least some examples R₂ and R₃ together with the nitrogen atom towhich they are bonded form a morpholinyl, pyridyl, piperidyl, pyrrolyl,pyrimidinyl, pyrolinyl, pyrrolidinyl, pyrazinyl or pyridazinyl group.

In at least some examples R₁ is a polybutyl or polyisobutyl groupcontaining 20 to 400 carbon atoms which is derived or derivable fromisobutene and up to 20% by weight n-butene.

In at least some examples R₁ is a polybutyl or polyisobutyl groupcontaining 32 to 200 carbon atoms which is derived or derivable fromisobutene and up to 20% by weight n-butene and R₂ and R₃ identical ordifferent and are each independently: hydrogen, methyl, ethyl, n-propyl,isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl, hexyl,phenyl, —CH₂—CH₂—NH₂, —CH₂—CH₂—CH₂—N(CH₃)₂, or—[—CH₂—CH₂—NH]_(p)—CH₂—CH₂—NH₂ where p is an integer from 1 to 7, forexample 1 to 3, —CH₂—CH₂—OH, —[—CH₂—CH₂—CH₂—OH where q is an integerfrom 1 to 30, or together with the nitrogen atom to which they arebonded, form a morpholinyl group.

Examples of suitable polyisobutylene amines additives also includepolyisobutylene amines disclosed in, and/or obtained or obtainable bymethods described in, described in U.S. Pat. No. 6,140,541 and U.S. Pat.No. 6,909,018. Thus, examples of suitable polyisobutylene amines includecompounds represented by the formula (V):

wherein R₇, R₈, R₉ and R₁₀ independently of one another, are eachhydrogen or an unsubstituted or substituted, saturated or mono- orpolyunsaturated aliphatic group exhibiting a number average molecularweight of up to 40000, at least one of the groups R₇ to R₁₀ exhibiting anumber average molecular weight of from 150 to 40000, and R₁₁ and R₁₂independently of each other are each H; an alkyl group, for example a C₁to C₁₈ alkyl group; a cycloalkyl group; a hydroxyalkyl group; anaminoalkyl group; an alkenyl group; an alkynyl group, an aryl group; anarylalkyl group; an alkylaryl group; a heteroaryl group; analkylene-imine group represented by the formula (VI):

wherein:

-   -   Alk is a straight-chain or branched alkylene    -   m is an integer from 0 to 10; and    -   R₁₃ and R₁₄, independently of one another, are each H; an alkyl        group, for example a C₁ to C₁₈ alkyl group; a cycloalkyl group;        a hydroxyalkyl group; an aminoalkyl group; an alkenyl group; an        alkynyl group, an aryl group; an arylalkyl group; an alkylaryl        group; a heteroaryl group or, together with the nitrogen atom to        which they are bonded, form a heterocyclic structure, or    -   R₁₁ and R₁₂, together with the nitrogen atom to which they are        bonded, form a heterocyclic structure.

In at least some examples, each of R₁₁, R₁₂, R₁₃ and R₁₄ areindependently substituted by further alkyl groups carrying hydroxy oramino groups.

Examples of suitable polyisobutylene amines additives also includepolyisobutylene amines disclosed in, and/or obtained or obtainable bymethods described in, U.S. Pat. No. 7,753,970. Thus, examples ofsuitable polyisobutylene amines include polyisobutylene amines that arederived or derivable from polyisobutenes derived or derivable fromisobutene or an isobutenic monomer mixture, for example a mixture ofisobutene and up to 20% by weight of n-butene. Suitable polyisobutyleneamines include polyisobutene amines derived or derivable frompolyisobutylene that is derived or derivable by the polymerisation ofidentical or different straight-chain or branched C₄ olefin monomers,which in at least some examples, are suitably randomised in thepolymerisation product. Suitable polyisobutylene amines includepolyisobutylene amines that are derived or derivable from highlyreactive polyisobutenes. Highly reactive polyisobutenes contain a highcontent of terminal double bonds (also sometimes referred toalpha-olefinic double bonds and/or vinylidene double bonds), for exampleat least 20%, or at least 50%, or at least 70% of the total olefinicdouble bonds in the polyisobutene. These are sometimes represented bythe general structure:

Highly reactive polyisobutenes may be made by methods described forexample in U.S. Pat. No. 4,152,499.

In at least some examples the polyisobutylene amine contains apolyisobutenic group that exhibits a number average molecular weight offrom about 200 to about 10000, for example from about 500 to about 5000or from about 700 to about 1500 or from about 800 to about 1200 or fromabout 850 to about 1100, for example about 1000.

In at least some examples, the polyisobutylene amine is derived from orderivable from a polyisobutene that exhibits at least one of thefollowing properties:

-   -   (i) being derivable or derived from isobutene and up to 20% by        weight of n-butene;    -   (ii) being derivable or derived from isobutenic mixture        containing at least 70 mol. % vinylidene double bonds based on        the total olefinic bonds in the polyisobutene;    -   (iii) containing at least 85% by weight isobutylene units;    -   (iv) a polydispersity in the range of from 1.05 to 7

Methods of making suitable polyisobutylene amines are described forexample in U.S. Pat. No. 4,832,702, U.S. Pat. No. 6,140,541, U.S. Pat.No. 6,909,018 and/or U.S. Pat. No. 7,753,970.

In at least some examples, more than one polyalkylene amine ispresent/used. Where more than one polyalkylene amine is present/used,each polyalkylene amine may be a polyisobutylene amine.

In at least some examples the polyalkylene amine is present/used in thefuel composition at a concentration of actives of at least about 50 ppm,for example at a concentration of actives of at least about 70 ppm. Inat least some examples the polyalkylene amine is present/used in thefuel composition at a concentration as actives of up to about 500 ppm,for example at a concentration of up to about 300 ppm. In at least someexamples the polyalkylene amine is present/used in the fuel compositionat a concentration of actives in the range of from about 50 ppm to about500 ppm, such as from about 70 ppm to about 300 ppm. Concentration ofactives means the concentration of the active polyalkylene aminedisregarding for example, any solvent and the like. As will be clear tothe skilled person, the concentration of actives expressed herein interms of ppm is ppm by weight.

Typically, the polyalkylene amine will be present/used in the fuelcomposition at a concentration of actives of from about 50 ppm to about160 ppm. In some examples, however, higher treat rates may be used. Insuch instances, the polyalkylene amine may be present/used in the fuelcomposition at a concentration of from about 160 ppm to about 500 ppm.

Where more than one polyalkylene amine is used, the total concentrationof the polyalkylene amines is as described herein.

Hydrocarbyl-Substituted Aromatic Compound.

The hydrocarbyl-substituted aromatic compound may be ahydrocarbyl-substituted hydroxyaromatic compound, such as ahydrocarbyl-substituted phenol compound. The hydrocarbyl substituent mayattach at the ortho-, meta- or para-position of the phenol ring.

The hydrocarbyl substituent of the hydrocarbyl-substituted aromaticcompound may exhibit a number average molecular weight of from about 700to about 1500, such as from about 900 to about 1300.

In embodiments, a Mannich Base additive may be used in the fuelcomposition.

Examples of Mannich Base additives include those obtained or obtainableby the reaction of a hydrocarbyl-substituted hydroxyaromatic compound,an amine and an aldehyde under Mannich condensation reaction conditions.Suitable reaction conditions include at least one (for example, all) ofthe following conditions:

-   -   at a temperature in the range of from 40° C. to 200° C.;    -   in the absence or presence of solvent;    -   for a reaction time in the range of from 2 to 4 hours; and    -   with azeotropic distillative removal of water by-product.

Examples of aldehydes suitable for the preparation of Mannich Baseadditives include:

-   -   aliphatic aldehydes, including for example, formaldehyde,        acetaldehyde, propionaldehyde, butyraldehyde, valeraldehyde,        caprioaldehyde, heptaldehyde and stearaldehyde;    -   aromatic aldehydes including for example, benzaldehyde and        salicylaldehyde; and heterocyclic aldehydes including for        example, furfural aldehyde and thiophene aldehyde.

Also useful in at least some examples are formaldehyde precursorsincluding for example paraformaldehyde and aqueous formaldehydesolutions including for example formalin.

Examples of representative hydrocarbyl substituents of thehydrocarbyl-substituted hydroxyaromatic compound include for example,polyolefin polymers for example polypropylene, polybutenes,polyisobutylene, ethylene alpha-olefin copolymers and the like. Otherexamples include copolymers of butylene and/or isobutylene and/orpropylene and one or more mono-olefinic comonomers copolymerisabletherewith (for example ethylene, 1-pentene, 1-hexene, 1-octene, 1-deceneand the like) where the comonomer molecule contains at least 50% byweight of butylene and/or isobutylene and/or propylene units. In someexamples the copolymers are aliphatic and in some examples containnon-aliphatic groups (for example styrene, o-methylstyrene,p-methylstyrene, divinyl benzene and the like), in any case theresulting polymers are substantially aliphatic hydrocarbon polymers.

Examples of suitable Mannich Base additives include Mannich Baseadditives in which the hydrocarbyl substituent of the aromatic group isor comprises polyisobutylene. Such compounds are sometimes calledPIB-Mannich Base additives.

In at least some examples hydrocarbyl substituents of thehydrocarbyl-substituted hydroxyaromatic compound include polymersobtained or obtainable from pure or substantially pure 1-butene;polymers obtained or obtainable from pure or substantially pureisobutene; and polymers obtained or obtainable from mixtures of1-butene, 2-butene and isobutene. In at least some examples thehydrocarbyl-substituted hydroxyaromatic reactant is obtained orobtainable from high reactive polyisobutene. High reactivepolyisobutenes contain a high content of terminal double bonds (alsosometimes referred to alpha-olefinic double bonds and/or vinylidenedouble bonds), for example at least 20%, or at least 50%, or at least70% of the total olefinic double bonds in the polyisobutene. Examples ofhigh reactivity polybutylenes containing relatively high proportions ofpolymer molecules comprising a terminal vinylidene group include thosethat are obtained or obtainable by methods described in U.S. Pat. No.4,152,499 and DE2904314.

In at least some examples the hydrocarbyl substituents contain someresidual unsaturation but in general they are substantially saturated.

In at least some examples the hydrocarbyl substituent is a polymerexhibiting a polydispersity of from 1 to 4, for example from 1 to 2, forexample as determined by gel permeation chromatography (sometimes alsoreferred to as GPC).

In some examples, the hydrocarbyl substituent of the hydroxyaromaticcompound used to prepare the Mannich Base additive, which in someinstances is or comprises polyisobutylene, may exhibit a number averagemolecular weight of from about 700 to about 1500, such as from about 900to about 1300.

Examples of suitable Mannich Base additives include those disclosed in,and/or obtained or obtainable by methods described in, U.S. Pat. No.5,634,951, U.S. Pat. No. 5,697,988, U.S. Pat. No. 6,800,103, U.S. Pat.No. 7,597,726 and/or US20090071065.

Examples of suitable Mannich Base additives include those disclosed in,and/or obtained or obtainable by methods described in, US5634951. Thus,examples of suitable Mannich Base additives include those obtainable orobtained by the reaction of (i) one mole part of at least onehydroxyaromatic compound comprising on the ring an aliphatic hydrocarbylsubstituent derived from a polyolefin exhibiting a number averagemolecular weight in the range of 500 to 3000, (ii) from 0.8 to 1.3 molepart(s) of at least one aldehyde, and (iii) from 0.8 to 1.5 mole part(s)of at least one aliphatic polyamine comprising in the molecule oneprimary or secondary amino group capable of undergoing a Mannichcondensation reaction with (i) and (ii), the other amino group or groups(if any) in the molecule being substantially inert towards participationin such Mannich condensation reaction, with the proviso that the moleratio of aldehyde to amine is 1.2 or less.

Examples of suitable hydroxyaromatic compounds (i) include highmolecular weight alkyl-substituted hydroxyaromatic compounds includingpolypropylphenol (including those formed by alkylating phenol withpolypropylene), polybutylphenols (including those formed by alkylatingphenol with polybutenes and/or polyisobutylene), andpolybutyl-co-polypropylphenols (including those formed by alkylatingphenol with a copolymer of butylene and/or isobutylene and propylene).Other hydroxyaromatic compounds include for example, long chainalkylphenols for example those made by alkylating phenol with copolymersof butylene and/or isobutylene and/or propylene and one or moremono-olefinic comonomers copolymerisable therewith (including forexample ethylene, 1-pentene, 1-hexene, 1-octene, 1-decene and the like),for example those in which the copolymer contains at least 50% by weightof butylene and/or isobutylene and/or propylene units. The comonomersmay be aliphatic and can also contain non-aliphatic groups (for examplestyrene, o-methylstyrene, p-methylstyrene, divinyl benzene and thelike). Suitable examples include polybutylphenols (for example, formedby alkylating phenol with polybutylene), which polybutylene includes forexample, polymers made from pure or substantially pure 1-butene orisobutene and mixtures made from two, or all three of 1-butene, 2-buteneand isobutene. High reactivity polybutylenes are also suitable examplesfor making suitable hydrocarbyl-substituted hydroxyaromatic compounds.Examples of hydrocarbyl-substituted hydroxyaromatic compounds includepara-substituted hydroxyaromatic compounds. Examples ofhydrocarbyl-substituted hydroxyaromatic compounds include those withone, two or more than two hydrocarbyl substituents.

Examples of suitable polyamine reactants (iii) include alkylenepolyamines for example containing a single reactive primary or secondaryamino group. Examples include those comprising other groups includingfor example hydroxyl, cyano, amido and etc. Examples of suitablepolyamines include aliphatic diamines, for example, those containing oneprimary or secondary amino group and one tertiary amino group. Examplesinclude N,N,N″,N″-tetraalkyldialkylenetriamines;N,N,N′,N″-tetraalkyltrialkylenetetramines;N,N,N′,N″,N′″-pentaalkyltrialkylenetetramines;N,N-dihydroxyalkyl-α,ω-alkylenediamines;N,N,N′-trihydroxyalkyl-α,ω-alkylenediamines;tris(dialkylaminoalkyl)aminoalkylmethanes etc. including those forexample, in which the alkyl groups are the same or different, includingthose that typically contain no more than 12 carbon atoms, for example 1to 4 carbon atoms each e.g. methyl and/or ethyl. Examples of polyaminescontaining one reactive primary or secondary amino group that canparticipate in the Mannich condensation reaction and at least onesterically hindered amino group that cannot participate directly in theMannich reaction include for example, N-(tert-butyl)-1,3-propanediamine;N-neopentyl-1,3-propranediamine;N-(tert-butyl)-1-methyl-1,2-ethanediamine;N-(tert-butyl)-1-methyl-1,3-propanediamine and3,5-di(tert-butyl)aminoethylpiperazine.

Examples of suitable Mannich Base additives also include those disclosedin, and/or obtained or obtainable by methods described in U.S. Pat. No.5,697,988. Thus, examples of suitable Mannich Base additives includeMannich reaction products of (i) a high molecular weightalkyl-substituted phenol, (ii) amine and (iii) aldehyde wherein (i),(ii) and (iii) are reacted in a ratio in the range of from1.0:0.1-10.0:0.1-10. In at least some examples the Mannich reactionproducts are obtained or obtainable by condensing an alkyl-substitutedhydroxyaromatic compound whose alkyl-substituent has a number averagemolecular weight (Mn) in the range of from 600 to 14000 for examplepolyalkylphenol whose polyalkyl substituent is derived or derivable from1-mono-olefin polymers exhibiting a number average molecular weight inthe range of from 600 to 3000, for example in the range of from 750 to1200; an amine containing at least one >NH group, for example analkylene polyamine as represented by the formula: H₂N-(A-NH-)_(x)H inwhich A is a divalent alkylene group containing 1 to 10 carbon atoms andx is an integer in the range of from 1 to 10; and an aldehyde, forexample formaldehyde in the presence of a solvent. Suitable reactionconditions include one or more of the following:

-   -   operating at a temperature in the range of from room temperature        to 95° C.;    -   reacting the compounds alone or in the presence of an easily        removable solvent for example benzene, xylene, toluene, or        solvent refined neutral oil;    -   using formaldehyde (e.g. formalin) as the aldehyde;    -   heating the reaction mixture at an elevated temperature (for        example 120° C. to 175° C.) whilst for example, blowing inert        stripping gas (e.g. nitrogen, carbon dioxide and the like) until        dehydration is complete; and    -   filtering the reaction product and diluting with solvent.

Examples of Mannich reaction products include those derived or derivableby reacting an alkylphenol, an ethylene polyamine and a formaldehyde inrespective molar ratio of 1.0:0.5-2.0:1.0-3.0 wherein the alky group ofthe alkyl phenol exhibits a number average molecular weight (Mn) in therange of from 600 to 3000, for example in the range of from 740 to 1200or in the range of from 800 to 950 or for example 900. Examples ofalkyl-substituted hydroxyaromatic compounds include para-substitutedmono-alkylphenols and ortho mono-alkylphenols and dialkyl phenols.Examples of amine reactants include polyamines, for example polyethyleneamines. Examples of amine reactants also include mono and di-aminoalkanes and their substituted analogs, for example ethylamine,dimethylamine, dimethylaminopropyl amine and diethanol amine; aromaticdiamines, (e.g. phenylene diamine and diamine naphthalenes);heterocyclic amines (e.g. morpholine, pyrrole, pyrrolidine, imidazole,imidazolidine and piperidine); melamine; and their substituted analogs.Examples of amine reactants include alkylene polyamines, for examplepolyamines that are linear, branched or cyclic; mixtures of linearand/or branched and/or cyclic polyamines wherein each alkylene groupcontains from 1 to 10 carbon atoms, for example from 2 to 20 carbonatoms. Examples of polyamines include those containing from 3 to 7nitrogen atoms.

Examples of suitable Mannich Base additives also include those disclosedin, and/or obtained or obtainable by methods described in, U.S. Pat. No.6,800,103. Thus, examples of suitable Mannich Base additives includethose obtained or obtainable by reacting a mixture of (i) at least onesubstituted hydroxyaromatic compound containing on the ring both (a) analiphatic hydrocarbyl substituent derived from a polyolefin exhibiting anumber average molecular weight in the range of 500 to 3000 and (b) aC₁₋₄ alkyl; (ii) at least one secondary amine; and (iii) at least onealdehyde. In at least some examples components (ii) and (iii) arepre-reacted to from an intermediate prior to addition of component (i).In at least some examples a mixture formed from components (i), (ii) and(iii) is heated at a temperature above 40° C. at which Mannichcondensation reaction takes place.

In at least some examples the Mannich reaction products is obtained orobtainable by reacting a di-substituted hydroxyaromatic compound inwhich the hydrocarbyl substituent (a) comprises polypropylene,polybutylene or an ethylene alpha-olefin copolymer exhibiting a numberaverage molecular weight in the range of 500 to 3000 and apolydispersity in the range of 1 to 4, one or more secondary amines andat least one aldehyde. In at least some examples there is used dibutylamine as the amine, formaldehyde or formalin as the aldehyde and a molarratio of the substituted hydroxyaromatic compound to dibutyl amine toformaldehyde of 1:0.8-1.5:0.8-1.5 respectively, for example1:0.9-1.2:0.9-1.2, respectively.

Examples of representative di-substituted hydroxyaromatic compoundsinclude those represented by the general formula (VII):

in which each R is H, C₁₋₄ alkyl or a hydrocarbyl substituent exhibitinga number average molecular weight in the range of 500 to 3000, with theproviso that one R is H, one R is a C₁₋₄ alkyl and one R is ahydrocarbyl substituent.

Examples of representative hydrocarbyl substituents of thehydrocarbyl-substituted hydroxyaromatic compound (ii) include polyolefinpolymers for example polypropylene, polybutenes, polyisobutylene,ethylene alpha-olefin copolymers and the like. Other examples includecopolymers of butylene and/or isobutylene and/or propylene and one ormore mono-olefinic comonomers copolymerisable therewith (for exampleethylene, 1-pentene, 1-hexene, 1-octene, 1-decene and the like) wherethe comonomer molecule contains at least 50% by weight of butyleneand/or isobutylene and/or propylene units. In some examples thecopolymers are aliphatic and in some examples contain non-aliphaticgroups (for example styrene, o-methylstyrene, p-methylstyrene, divinylbenzene and the like), in any case the resulting polymers aresubstantially aliphatic hydrocarbon polymers. High reactivitypolybutylenes are also suitable for making suitablehydrocarbyl-substituted hydroxyaromatic compounds.

Examples of suitable di-substituted hydroxyaromatic compounds includethose obtained or obtainable by alkylating o-cresol with the highmolecular weight polymers described above.

Suitably in at least some examples, the hydrocarbyl substituent is inthe para-position of the disubstituted hydroxyaromatic compound and theC₁₋₄ alkyl substituent is in the ortho-position.

Examples of representative secondary amines (ii) include thoserepresented by the general formula (VIII):

in which R′ and R″ are each independently alkyl, cycloalkyl, aryl,alkaryl or aralkyl groups containing from 1 to 30 carbon atoms, forexample 1 to 18 carbon atoms or 1 to 6 carbon atoms. Examples includedimethylamine, diethylamine, dipropylamine, dibutylamine, dipentylamineand dicyclohexylamine.

Examples of suitable Mannich Base additives also include those disclosedin, and/or obtained or obtainable by methods described in U.S. Pat. No.7,597,726. Thus, examples of suitable Mannich Base additives includeMannich condensation reaction products of (i) a polyamine containing asterically-hindered primary amino group, (ii) a hydrocarbyl-substitutedhydroxyaromatic compound and (iii) and aldehyde. Examples of polyamines(i) containing a sterically-hindered primary amino group include (A)aliphatic cyclic polyamines containing a sterically-hindered primaryamino group, (B) acyclic aliphatic polyamines containing asterically-hindered primary amino group and combinations thereof. In atleast some examples the Mannich reaction product is obtained orobtainable by reacting (1) 1,2-diaminocyclohexane, (2)polyisobutylene-substituted cresol and/or phenol, and (3) formaldehyde,for example in which the reactants (1), (2) and (3) are reacted inequimolar proportions in a Mannich reaction. In at least some examplesthe Mannich reaction product is dispersed in a liquid carrier fluid. Inat least some examples the polyamine reactant contains an amino groupthat does not participate in the Mannich condensation reaction with thehydrocarbyl-substituted hydroxyaromatic reactant in addition to at leastone reactive amino group in the same polyamine molecule that takes partin the Mannich reaction. Examples of reactive amino groups includeprimary and secondary amino groups, for example non-sterically hinderedreactive primary amino groups. Examples of polyamines containing areactive amino group and a sterically-hindered amino group include thoserepresented by the formula (IX):

wherein X and Z each is methylene, Y is an alkylene or alkyleneaminogroup, n is 0 or 1, Q is an optional alkylene group suitable for forminga ring structure with X and Z, E is a hydrocarbyl group, t is 0 or 1, R¹is a hydrocarbyl group or hydrogen provided that R¹ is hydrocarbyl if nis 1, R² is hydrogen or a hydrocarbyl group, m is 0 or 1 provided that mis 0 if Q is present. If R¹ and/or R² is hydrocarbyl, examples of suchhydrocarbyl groups include C₁ to C₈ alkyl (for example methyl, ethyl,propyl, isopropyl, t-butyl and the like). Where n is 1, examples of Yinclude C₁ to C₈ alkylene; alkyleneamino (for example methyleneamino,(—CH₂N(H)—), dimethyleneamino (—CH₂N(H)—CH₂—),methyleneamino-ethylmethyleneamino (—CH₂N(H)—C₂H₄N(H)—CH₂—) and thelike). Where t is 1, examples of E include methylene, ethylene,isopropylene and the like. Examples of Q include alkylene chains, forexample C₂-C₄ alkylene chains. Examples of polyamines containing asterically hindered primary amino group include aliphatic cyclicpolyamines, including for example, polyaminocycloalkanes, for examplepolyaminocyclohexanes, including 1,2-diaminodicyclohexanes,1,3-diaminodicyclohexanes and 1,4-diaminodicyclohexanes, for example asrepresented by the following formulae Xa, Xb and Xc:

In at least some examples in the aliphatic cyclic polyamine structure, asterically hindering hydrocarbyl group generally is bonded to the samecarbon atom from which the sterically-hindered primary amino group isbonded when the hindered/protected and reactive amino groups are presentin an arrangement other than an ortho configuration relative to eachother. In at least some examples (for example compound Xc), a reactiveamino group is present as a moiety of an intervening substituent that isdirectly attached to the ring structure. In at least some examplesmixtures of isomers are used. Examples of suitable acyclic aliphaticpolyamine reactants include alkylene polyamines containing a primaryamino group that is physically sterically-protected to prevent or atleast significantly hinder its ability to participate in the Mannichcondensation reaction. In at least some examples the sterically hinderedprimary amino group is generally attached to either a secondary ortertiary carbon atom in the polyamine compound. The acyclic aliphaticpolyamine has a suitably reactive amino group (for example primary orsecondary) in the same molecule for participating in the Mannichcondensation reaction. In at least some examples other substituents arepresent, for example hydroxyl, cyano, amido and the like. Examples ofacyclic aliphatic polyamines containing a sterically hindered primaryamino group include those represented by formulae XIa, XIb, XIc and XId:

wherein each R₁ and R₂ are a hydrocarbyl group or a hydrogen providedthat at least one thereof is a hydrocarbyl group. Examples ofhydrocarbyl groups include C₁ to C₈ alkyl e.g. methyl, ethyl, propryl,isopropyl and the like;

Examples of hydrocarbyl-substituted hydroxyaromatic compounds (ii)include those represented by formula XII:

in which each R is H, C₁₋₄ alkyl or a hydrocarbyl substituent exhibitingan average molecular weight (Mw) in the range of 300 to 2000, forexample 500 to 1500, for example as measured by gel permeationchromatorgraphy, with the proviso that at least one R is H and one R isa hydrocarbyl substituent as hereinbefore defined.

Examples of representative hydrocarbyl substituents of thehydrocarbyl-substituted hydroxyaromatic compound (ii) include polyolefinpolymers for example polypropylene, polybutenes, polyisobutylene,ethylene alpha-olefin copolymers and the like. Other examples includecopolymers of butylene and/or isobutylene and/or propylene and one ormore mono-olefinic comonomers copolymerisable therewith (for exampleethylene, 1-pentene, 1-hexene, 1-octene, 1-decene and the like) wherethe comonomer molecule contains at least 50% by weight of butyleneand/or isobutylene and/or propylene units. In some examples thecopolymers are aliphatic and in some examples contain non-aliphaticgroups (for example styrene, o-methylstyrene, p-methylstyrene, divinylbenzene and the like), in any case the resulting polymers aresubstantially aliphatic hydrocarbon polymers.

In at least some examples hydrocarbyl substituents include polymersobtained or obtainable from pure or substantially pure 1-butene;polymers obtained or obtainable from pure or substantially pureisobutene; and polymer obtained or obtainable from mixtures of 1-butene,2-butene and isobutene. In at least some examples thehydrocarbyl-substituted hydroxyaromatic reactant is obtained orobtainable from highly reactive polyisobutene.

In at least some examples a suitable di-substituted hydroxyaromaticcompound is obtained or obtainable by alkylating o-cresol with a highmolecular weight hydrocarbyl polymer, for example a hydrocarbyl polymerexhibiting an average molecular weight in the range of from 300 to 2000,for example by alkylating o-cresol or o-phenol with polyisobutyleneexhibiting an average molecular weight in the range of from 300 to 2000,for example in the range of from 500 to 1500.

Examples of suitable Mannich Base additives also include those disclosedin, and/or obtained or obtainable by methods described in US20090071065.Thus, examples of suitable Mannich Base additives include Mannichcondensation reaction products of: (i) a polyamine having primary aminogroups, (ii) a hydrocarbyl-substituted hydroxyaromatic compound, and(iii) an aldehyde, where the Mannich reaction is conducted at an overallmolar ratio of (i):(ii):(iii) such that, for example, the polyamine (i)is reactable with the hydrocarbyl-substituted hydroxyaromatic compound(ii) so as to obtain the substantially pure intermediate, whichintermediate is reactable with the aldehyde (iii) to obtain the Mannichreaction product, for example in a one-pot reaction process. Examples ofpolyamine (i) include 1,2-diaminocyclohexane, 1,3-diamino propane and1,2-diamino ethane. Examples of suitable molar ratios (i):(ii):(iii)include 1:2:3 and 1:1:2. Examples of hydrocarbyl-substitutedhydroxyaromatic compounds include those represented by formula (XIII):

in which each R is H, C₁₋₄ alkyl, or a hydrocarbyl substituentexhibiting an average molecular weight (Mw) in the range of 300 to 2000,for example 500 to 1500, for example as determined by gel permeationchromatography, with the proviso that at least R is H and one R is ahydrocarbyl substituent as hereinbefore defined. Examples of hydrocarbylsubstituents include polyolefin polymers, for example polypropylene,polybutylene, polyisobutylene and ethylene alpha-olefin copolymers andalso copolymers of butylene and/or isobutylene and/or propylene and oneor more mono-olefinic comonomers copolymerisable therewith (for exampleethylene, 1-pentene, 1-hexene, 1-octene, 1-decene and the like) whereinthe copolymer contains at least 50% by weight of butylene and/orisobutylene and/or propylene units. In at least some examples polyolefinpolymer hydrocarbyl substituents contain at least 20%, for example 50%,or 70% of their olefin double bonds at a terminal position on the carbonchain as the highly reactive vinylidene isomer. Examples of hydrocarbylsubstituents include those obtained or obtainable from polyisobutylene,for example polyisobutylene obtained or obtainable from pure orsubstantially pure 1-butene or isobutene and polymers obtained orobtainable from mixtures of two or three of 1-butene, 2-butene andisobutene. Examples of hydrocarbyl substituents include those obtainedor obtainable from high reactivity polyisobutylene which have arelatively high proportion of polymer having terminal vinylidene groups,for example at least 20%, 50% or 70% of the total terminal olefinicdouble bonds in the polyisobutylene comprise an alkyl vinylidene isomer.

In at least some examples, more than one hydrocarbyl-substitutedaromatic compound is present/used. Where more than onehydrocarbyl-substituted aromatic compound is present/used, eachhydrocarbyl-substituted aromatic compound may be a Mannich baseadditive.

In at least some examples the hydrocarbyl-substituted aromatic compoundis present/used in the fuel composition at a concentration of actives ofat least about 20 ppm, for example at a concentration of actives of atleast about 30 ppm. In at least some examples, thehydrocarbyl-substituted aromatic compound is present/used in the fuelcomposition at a concentration of actives of up to about 300 ppm, forexample at a concentration of up to about 120 ppm. In at least someexamples, the hydrocarbyl-substituted aromatic compound is present/usedin the fuel composition at a concentration of actives in the range offrom about 20 ppm to about 300 ppm, such as from about 30 ppm to about120 ppm. Concentration of actives means the concentration of the activehydrocarbyl-substituted aromatic compound disregarding, for example, anysolvent and the like.

Typically, the hydrocarbyl-substituted aromatic compound will bepresent/used in the fuel composition at a concentration of actives offrom about 20 ppm to about 70 ppm. In some examples, however, highertreat rates may be used. In such instances, the hydrocarbyl-substitutedaromatic compound may be present/used in the fuel composition at aconcentration of from about 70 ppm to about 300 ppm.

Where more than one hydrocarbyl-substituted aromatic compound ispresent/used, the total concentration of the hydrocarbyl-substitutedaromatic compounds is as described herein.

In some examples, the polyalkylene amine is present/used in the fuelcomposition at a concentration of actives of from about 50 ppm to about500 ppm and the hydrocarbyl-substituted aromatic compound ispresent/used in the fuel composition at a concentration of actives offrom about 20 ppm to about 300 ppm. Typically, the polyalkylene aminemay be present/used in the fuel composition at a concentration ofactives of from about 50 ppm to about 160 ppm and thehydrocarbyl-substituted aromatic compound may be present/used in thefuel composition at a concentration of actives of from about 20 ppm toabout 70 ppm. However, in some examples, the polyalkylene amine may bepresent/used in the fuel composition at a concentration of actives offrom about 160 ppm to about 500 ppm and the hydrocarbyl-substitutedaromatic compound may be present/used in the fuel composition at aconcentration of actives of from about 70 ppm to about 300 ppm.

In at least some examples the weight ratio of actives of thepolyalkylene amine: the hydrocarbyl-substituted aromatic compound is inthe range of about 10:1 to about 1:10 for example about 5:1 to about1:5. Where more than one polyalkylene amine and/or more than onehydrocarbyl-substituted aromatic compound is present/used, the weightratio of actives of all of the polyalkylene amines: all of thehydrocarbyl-substituted aromatic compound is as described herein.

Typically, the polyalkylene amine, contains a polyalkylene group thatexhibits a number average molecular weight of from about 700 to about1500 (e.g. from about 800 to about 1200) and the hydrocarbyl substituentof the hydrocarbyl-substituted aromatic compound, which in someinstances is or comprises polyisobutylene, exhibits a number averagemolecular weight of from about 700 to about 1500 (e.g. about 900 toabout 1300).

Carrier Fluid.

In at least some examples, a carrier fluid (sometimes also calledinduction aid or fluidiser) is present/used in the fuel composition, theuses and/or the methods. In at least some examples more than one carrierfluid is present/used.

In at least some examples the carrier fluid is provided with thepolyalkylene amine. In at least some examples the carrier fluid isprovided with the hydrocarbyl-substituted aromatic compound. In at leastsome examples a carrier fluid is provided with each of the polyalkyleneamine and the hydrocarbyl-substituted aromatic compound, which carrierfluids may be the same or different. In at least some examples thecarrier fluid is provided independently of the polyalkylene amine andthe hydrocarbyl-substituted aromatic compound.

Examples of suitable carrier fluids are described for example inUS2009/0071065 at paragraphs [0038] to [0053]. Thus, examples ofsuitable carrier fluid include liquid poly-alpha olefin oligomers,liquid polyalkene hydrocarbons (for example polypropylene, polybutenes,polyisobutene and the like), liquid hydrotreated polyalkene hydrocarbons(for example hydrotreated polypropylene, hydrotreated polybutenes,hydrotreated polyisobutene and the like), mineral oils, liquidpoly(oxyalkylene) compounds, liquid alcohols, liquid polyols, liquidesters and the like.

Examples of carrier fluids include (1) a mineral oil or blend of mineraloils, for example those exhibiting a viscosity index of less than 120;(2) one or a blend of poly alpha olefins, for example those exhibitingan average molecular weight in the range of from 500 to 1500; (3)polyethers including poly(oxyalkylene) compounds, for example thoseexhibiting an average molecular weight in the range of from 500 to 1500;(4) one or more liquid polyalkylenes; and (5) mixtures of two or moreselected from the group consisting of (1), (2), (3) and (4).

Examples of suitable mineral oil carrier fluids include paraffinic,naphthenic and asphaltic oils, for example hydrotreated oils. Examplesof mineral oils exhibit a viscosity at 40° C. of less than 1600 SUS, forexample 300 to 1500 SUS and/or exhibit a viscosity index of less than100, for example in the range 30 to 60.

Examples of suitable poly alpha olefin carrier fluids includehydrotreated and unhydrotreated poly alpha olefins. Examples of polyalpha olefins include trimmers, tetramers and pentamers of alpha olefinmonomers containing 6 to 12 carbon atoms.

Examples of suitable polyether carrier fluids include poly(oxyalkylene)compounds exhibiting an average molecular weight in the range of from500 to 1500, including for example hydrocarbyl-terminatedpoly(oxyalkylene) monols. Examples of poly(oxyalkylene) compoundsinclude one or a mixture of alkylpoly(oxyalkylene)monols which in itsundiluted state is a gasoline-soluble liquid exhibiting a viscosity ofat least 70 cSt at 40° C. and at least 13 cSt at 100° C., including suchmonols formed by propoxylation of one or a mixture of alkanolscontaining at least 8 carbon atoms, for example 10 to 18 carbon atoms.

Examples of suitable poly(oxyalkylene) carrier fluids include thoseexhibiting a viscosity in the undiluted state of at least 60 cSt at 40°C. (for example at least 70 cSt at 40° C.) and at least 11 cSt at 100°C. (for example at least at least 13 cSt at 100° C.). Examples ofsuitable poly(oxyalkylene) carrier fluids include those exhibitingviscosities in their undiluted state of no more than 400 cSt at 40° C.(for example no more than 300 cSt at 40° C.) and no more than 50 cSt at100° C. (for example no more than 40 cSt at 100° C.).

Examples of poly(oxyalkylene) compounds include poly(oxyalkylene) glycolcompounds and monoether derivatives thereof, for example those thatsatisfy the above viscosity requirements, including those that areobtained or obtainable by reacting an alcohol or polyalcohol with analkylene oxide, for example propylene oxide and/or butylene oxide withor without the use of ethylene oxide, for example products in which atleast 80 mol. % of the oxyalkylene groups in the molecule are derived orderivable from 1,2-propylene groups.

Examples of poly(oxyalkylene) compounds include those disclosed in,and/or obtained or obtainable by methods described in, U.S. Pat. No.248,664, U.S. Pat. No. 2,425,845, U.S. Pat. No. 2,425,755 and U.S. Pat.No. 2,457,139.

The poly(oxyalkylene) carrier compounds should contain sufficientbranched oxyalkylene units (for example methyldimethyleneoxy unitsand/or ethyldimethyleneoxy units) to render the poly(oxyalkylene)compound gasoline soluble.

Examples of polyalkylene carrier fluids include polypropenes,polybutenes, polyisobutenes, polyamylenes, copolymers of propene andbutene, copolymers of butene and isobutene, copolymers of propene andisobutene and copolymers of propene, butene and isobutene and mixturesthereof.

Examples of polyalkylene carrier fluids also include hydrotreatedpolypropylenes, hydrotreated polybutenes, hydrotreated polyisobutenesand the like.

Examples of polybutenes carrier fluids include those exhibiting a narrowmolecular weight distribution, for example as expressed as the ratioMw/Mn that is, (mass average molecular mass)/(the number averagemolecular mass), this ratio is sometimes called the polydispersityindex. Examples of polybutenes carrier fluids include those exhibiting anarrow molecular weight distribution, expressed as the ratio Mw (massaverage molecular mass)/Mn the number average molecular mass of 1.4 orless, for example as described in U.S. Pat. No. 6,048,373. Methods ofdetermining mass average molecular mass include static light scattering,small angle neutron scattering, X-ray scattering, and sedimentationvelocity. Number average molecular mass or weight (Mn) can be determinedby gel permeation chromatography.

In at least some examples the carrier fluid is present/used in the fuelcomposition at a concentration of at least about 10 ppm, for example ata concentration of at least about 35 ppm. In at least some examples, thecarrier fluid is present/used in the fuel composition at a concentrationof up to about 500 ppm, for example at a concentration of up to about200 ppm. In at least some examples, the carrier fluid is present/used inthe fuel composition at a concentration in the range of from about 10ppm to about 500 ppm, such as from about 35 ppm to about 200 ppm.

Where more than one carrier fluid is present/used, the totalconcentration of the carrier fluid is as described herein.

Fuel Composition

The fuel composition is suitable for use for example, in a sparkignition internal combustion engine or a compression-ignition gasolineinternal combustion engine.

In at least some examples the fuel composition has a sulphur content ofup to 50.0 ppm by weight, for example up to 10.0 ppm by weight.

Examples of suitable fuel compositions include leaded and unleaded fuelcompositions.

In at least some examples the fuel composition meets the requirements ofEN 228, for example as set out in BS EN 228:2012. In at least someexamples the fuel composition meets the requirements of ASTM D 4814-14.

In at least some examples the fuel composition for spark-ignitioninternal combustion engines exhibits one or more (for example all) ofthe following, for example, as defined according to BS EN 228:2012:—aminimum research octane number of 95.0, a minimum motor octane number of85.0 a maximum lead content of 5.0 mg/l, a density of 720.0 to 775.0kg/m³, an oxidation stability of at least 360 minutes, a maximumexistent gum content (solvent washed) of 5 mg/100 ml, a class 1 copperstrip corrosion (3 h at 50° C.), clear and bright appearance, a maximumolefin content of 18.0% by weight, a maximum aromatics content of 35.0%by weight, and a maximum benzene content of 1.00% by volume.

Examples of suitable fuel compositions include for example hydrocarbonfuels, oxygenate fuels and combinations thereof.

Hydrocarbon fuels may be derived from mineral sources and/or fromrenewable sources such as biomass (e.g. biomass-to-liquid sources)and/or from gas-to-liquid sources and/or from coal-to-liquid sources.

Examples of suitable oxygenate fuel components in the fuel compositioninclude straight and/or branched chain alkyl alcohols having from 1 to 6carbon atoms, for example methanol, ethanol, n-propanol, n-butanol,isobutanol, tert-butanol. Suitable oxygenate components in the fuelcomposition for spark-ignition internal combustion engines orcompression-ignition gasoline internal combustion engines includeethers, for example having 5 or more carbon atoms, for example methyltert-butyl ether and ethyl tert-butyl ether. In at least some examplesthe fuel composition has a maximum oxygen content of 2.7% by mass. In atleast some examples fuel composition has maximum amounts of oxygenatesas specified in EN 228, for example methanol: 3.0% by volume, ethanol:5.0% by volume, iso-propanol: 10.0% by volume, iso-butyl alcohol: 10.0%by volume, tert-butanol: 7.0% by volume, ethers (for example having 5 ormore carbon atoms): 10% by volume and other oxygenates (subject tosuitable final boiling point): 10.0% by volume. In at least someexamples fuel composition comprises ethanol complying with EN 15376 at aconcentration of up to 15% by volume, for example up to 10% by volume orup to 5.0% by volume. Examples of oxygenate-containing fuel compositionsinclude E5, E10, E15 and fuel compositions containing ethanol at higherconcentrations, for example up to E85

According to an aspect of the present invention there is provided amethod of reducing the sludge forming tendency of a fuel composition foruse in a spark-ignition internal combustion engine or acompression-ignition gasoline internal combustion engine which methodcomprises incorporating into the fuel composition in one or more steps:

a. a hydrocarbyl-substituted aromatic compound; and

b. a polyalkylene amine

to produce a fuel composition which comprises said additives incombination and which on use in said engine produces less sludge thanthe sludge formed when using in said engine the fuel composition withoutsaid combination of additives.

In at least some examples, the hydrocarbyl-substituted aromatic compoundand the polyalkylene amine are incorporated into the fuel compositionseparately or together as components of one or more additiveconcentrates, one or more additive packages and/or one or more additivepart packs.

In at least some examples the fuel composition and/or additiveconcentrates, and/or additive packages and/or additive part packscomprise at least one other fuel additive. In at least some examples themethod of reducing the sludge forming tendency of a fuel compositioncomprises incorporating in one or more steps at least one other fueladditive.

In at least some examples the additives are admixed and/or incorporatedas one or more additive concentrates and/or additive part packs,optionally comprising solvent or diluent.

In at least some examples, the fuel composition is prepared by admixingin one or more steps, one or more base fuels (for example hydrocarbonfuels, oxygenate fuels and combinations thereof) and componentstherefor, optionally with one or more additives and/or part additivepackage concentrates. In at least some examples, the additives, additiveconcentrates and/or part additive package concentrates are admixed withthe fuel or components therefor in one or more steps.

Examples of such other fuel additives include friction modifiers,anti-wear additives, corrosion inhibitors, dehazers/demulsifiers, dyes,markers, odorants, octane improvers, combustion modifiers,anti-oxidants, anti-microbial agents, lubricity improvers and valve seatrecession additives.

Representative suitable and more suitable independent amounts ofadditives (if present) in the fuel composition are given in Table 1. Theconcentrations expressed in Table 1 are by weight of active additivecompounds that is, independent of any solvent or diluent.

In at least some examples, more than one of each type of additive ispresent. In at least some examples, within each type of additive, morethan one class of that type of additive is present. In at least someexamples more than one additive of each class of additive is present. Inat least some examples additives are suitably supplied by manufacturersand/or suppliers in solvent or diluents.

TABLE 1 Fuel Composition Suitable amount More suitable amount (actives),(actives), if present ADDITIVE TYPE (by weight) (by weight)Hydrocarbyl-substituted 20-300 ppm 30-120 ppm aromatic compoundsPolyalkylene amines 50-500 ppm 70-300 ppm Carrier fluid 10-500 ppm35-200 ppm Friction modifiers/anti- 10-200 ppm wear additives Corrosioninhibitors 1-20 ppm Octane improvers and/or 5-3000 ppm combustionimprovers Anti-oxidants 0.1-20 ppm Dehazers/demulsifiers 0.1-20 ppm Dyesand/or markers 0.1-20 ppm Odorants 1-20 ppm Anti-microbial agents 1-20ppm Lubricity improvers 10-200 ppm Valve seat recession 1-1500 ppmadditives

Examples of suitable friction modifiers and anti-wear additives includethose that are ash-producing additives or ashless additives. Examples offriction modifiers and anti-wear additives include esters (for exampleglycerol mono-oleate) and fatty acids (for example oleic acid andstearic acid).

Examples of suitable corrosion inhibitors include ammonium salts oforganic carboxylic acids, amines and heterocyclic aromatics, for examplealkylamines, imidazolines and tolyltriazoles.

Examples of suitable non-metallic octane improvers include N-methylaniline.

Examples of suitable metal-containing octane improvers includemethylcyclopentadienyl manganese tricarbonyl, ferrocene and tetra-ethyllead. Suitably, the fuel composition is free of all added metallicoctane improvers including methyl cyclopentadienyl manganese tricarbonyland other metallic octane improvers including for example, ferrocene andtetraethyl lead.

Examples of suitable anti-oxidants include phenolic anti-oxidants (forexample 2,4-di-tert-butylphenol and3,5-di-tert-butyl-4-hydroxyphenylpropionic acid) and aminicanti-oxidants (for example para-phenylenediamine, dicyclohexylamine andderivatives thereof).

Examples of suitable valve seat recession additives include inorganicsalts of potassium or phosphorus.

In at least some examples the additive composition comprises solvent.Examples of suitable solvents include polyethers and aromatic and/oraliphatic hydrocarbons, for example heavy naphtha e.g. Solvesso (Trademark), xylenes and kerosene.

In at least some examples the additives are present in the fuelcomposition at a total amount in the range of 20 to 25000 ppm by weight.Therefore, the concentrations of each additive in an additiveconcentrate will be correspondingly higher than in the fuel composition,for example by a ratio of 1:0.00002 to 0.025. In at least some examplesthe additives are used as part-packs, for example part of the additives(sometimes called refinery additives) being added at the refinery duringmanufacture of a fungible fuel and part of the additives (sometimescalled terminal or marketing additives) being added at a terminal ordistribution point.

In at least some examples the hydrocarbyl-substituted aromatic compoundand the polyalkylene amine are incorporated or admixed with othercomponents of the fuel composition as a refinery additive or as amarketing additive.

In at least some examples the hydrocarbyl-substituted aromatic compoundand the polyalkylene amine are incorporated or admixed with othercomponents of the fuel composition as a marketing additive, for exampleat a terminal or distribution point.

In general, there are two types of spark-ignition, internal combustionengines which are classified according to the type of system fordelivering fuel to the engine combustion chambers.

Port Fuel Injection (PFI) engines are engines in which a mixture of fueland air is injected into intake ports and then passes into combustionchambers of the engine through one or more intake valves (sometimes alsocalled inlet valves or inlet port valves). Examples of suitable portfuel injection, spark-ignition internal combustion engines include anysuitable port fuel injection, spark-ignition internal combustion engineincluding for example BMW 318i engine, Ford 2.3L Ranger engine and MBM111 engine.

Direct Injection (DI) engines are engines in which fuel is injecteddirectly into combustion chambers of the engine through injectors(sometimes also called direct injectors or direct injector nozzles) andair is introduced into the combustion chambers through one or more airintake valves (sometimes also called air inlet valves or air inlet portvalves). Examples of suitable direct injection spark-ignition internalcombustion engines include boosted direct injection spark-ignitioninternal combustion engines, for example turbocharged boosted directinjection engines and supercharged boosted direct injection engines.Suitable engines include 2.0L boosted direct injection spark-ignitioninternal combustion engines. Suitable direct injection engines includethose that have side mounted direct injectors and/or centrally mounteddirect injectors.

The fuel compositions disclosed herein preferably control the overallformation of sludge in the engine, referred to herein as engine sludge.

The fuel compositions may also control the formation of sludge onparticular components of the engine, including the rocker cover(s), thecamshaft baffle, the timing chain cover, the oil pan and its baffle, theoil screen and the valve deck area. In examples, the fuel compositionscontrol the formation of rocker cover sludge.

Methods for assessing the sludge control performance of a fuelcomposition include those based upon the US industry standard testmethod: ASTM D-6593 (version 10), this is sometimes also called the Ford4.6L “Sequence VG” engine test. This test is used for determining theperformance of lubricants. However, the performance of fuels may betested by using the standard reference lubricant as the lubricant, andthe standard reference base fuel with the additives of interest addedthereto as the fuel. This test may be used to measure engine sludge(referred to in the test as ‘average engine sludge’) and rocker coversludge.

The fuel compositions used in the present invention control sludgeformation, but it is desirable that they also exhibit good detergency inthe rest of the engine, for instance on an intake valve. This may bedetermined by measuring intake valve keep-clean performance of the fuelcomposition. Methods of measuring the intake valve deposit keep-cleanperformance of a fuel composition for use in a spark-ignition internalcombustion engine include those based upon the US industry standard testmethod: ASTM D-6201 (version 04, 2009), this is sometimes also calledthe Ford 2.3L “Ranger” engine test after the engine that is used.

Further aspects of the present invention include the aspects,embodiments, instances and examples defined above but in which a MannichBase additive is used as component a. In these aspects, the Mannich Baseadditive may be, but does not have to be, a hydrocarbyl-substitutedaromatic compound.

The invention will now be described by way of example only withreference to the following drawing, experiment and example in whichExample 1 is according to the present invention and Experiment A is notaccording to the present invention.

In the drawing FIG. 1 represents, in graph form, the sludge controlperformance for the fuel compositions tested relative to a base fuelreference.

Intake valve deposit (IVD) keep-clean performance were assessed usingthe US industry standard test method: ASTM D-6201 (version 04, 2009)using a Ford 2.3 L port fuel injection spark-ignition internalcombustion engine. Intake valve deposit (IVD) keep-clean performance wasstudied using an El 0 gasoline base fuel.

Engine sludge and rocker cover sludge formation was assessed using theUS industry standard test method: ASTM D-6593 (version 20100628) using aFord 4.6L port fuel injection spark-ignition internal combustion engine.The standard reference fuel in ASTM D-6593, with additives of interestadded therein, was used as the fuel.

Experiment A—Polyisobutylene Only

The engine sludge and rocker cover sludge control performance of a fuelcontaining PIBA additive was assessed. The amount of PIBA used in theexperiment was selected to give a typical port fuel injection valvekeep-clean performance.

The engine sludge and rocker cover sludge control performance is shownin graph form in FIG. 1 as relative % sludge control performance(relative to a base fuel reference).

EXAMPLE 1 Combination of Mannich Base Additive and Polyisobutylene Amine

The engine sludge and rocker cover sludge control performance of a fuelcontaining a combination of Mannich Base additive and PIBA additive wasassessed. The amount of Mannich Base additive and PIBA used in theexperiment was selected to give a typical port fuel injection valvekeep-clean performance which was comparable to that of the fuelcomposition used for Experiment A.

The engine sludge and rocker cover sludge control performance is shownin graph form in FIG. 1 as relative % sludge control performance(relative to a base fuel reference).

The data generated in Experiment A and Example 1 are shown in Table 2.

TABLE 2 Keep-clean Treat rate Engine sludge control performance(arbitrary performance (% relative (arbitrary units mass to base fuelreference)* units) per volume) Engine Rocker cover Experiment A 10.020.0 113% 100% Example 1 9.9 18.9 115% 103% *a high number indicatesbetter control performance

The data shown in Table 2 and in FIG. 1 show that the fuel compositioncomprising Mannich Base additive in combination with a polyisobutyleneamine exhibits beneficial sludge control in a spark-ignition internalcombustion engine. In particular, the data show that the fuelcomposition comprising a Mannich Base additive in combination with apolyisobutylene amine exhibits greater sludge control in aspark-ignition internal combustion engine than an un-additised fuel anda fuel containing only polyisobutylene amine. The comparison with thefuel containing polyisobutylene amine is made for example atconcentrations of additives providing comparable detergency performance,when measured using a Ford 2.3 L port fuel injection spark-ignitioninternal combustion engine according to the industry standard testmethod: ASTM D-6201.

These data illustrate a method of controlling sludge formation in aspark-ignition internal combustion engine which method comprisessupplying to the engine a fuel composition which comprises a combinationof:

a. a hydrocarbyl-substituted aromatic compound; and

b. a polyalkylene amine.

The data also illustrate the use as a sludge controlling additive in afuel composition for a spark-ignition internal combustion engine of:

a. a hydrocarbyl-substituted aromatic compound; and

b. a polyalkylene amine.

The data also illustrate a method of reducing the sludge formingtendency of a fuel composition for use in a spark-ignition internalcombustion engine which method comprises incorporating into the fuelcomposition in one or more steps:

a. a hydrocarbyl-substituted aromatic compound; and

b. a polyalkylene amine

to produce a fuel composition which comprises said additives incombination and which on use in a spark-ignition internal combustionengine produces less sludge than the sludge formed when using in saidengine the fuel composition without said combination of additives.

The data also illustrate that the sludge control performance of a fuelcomposition comprising a combination of a hydrocarbyl-substitutedaromatic compound and a polyalkylene amine is improved relative to thatof a fuel composition which comprises a polyalkylene amine, but does notcomprise a hydrocarbyl-substituted aromatic compound. The sludge controlperformance of a fuel composition comprising a combination of ahydrocarbyl-substituted aromatic compound and a polyalkylene amine mayalso be improved relative to that of a fuel composition which comprisesa hydrocarbyl-substituted aromatic compound, but does not comprise apolyalkylene amine. Accordingly, in some examples, an additivecomposition comprising a combination of:

a. a hydrocarbyl-substituted aromatic compound; and

b. a polyalkylene amine

is used for improving the sludge control performance of a fuelcomposition in a spark-ignition internal combustion engine.

1-15. (canceled)
 16. A method of controlling sludge formation in aspark-ignition internal combustion engine or a compression-ignitiongasoline internal combustion engine which method comprises supplying tothe engine a fuel composition which comprises a combination of: a. ahydrocarbyl-substituted aromatic compound; and b. a polyalkylene amine,the hydrocarbyl-substituted aromatic compound and the polyalkylene aminebeing present in the fuel composition in an amount such thatsubstantially less sludge is formed when the fuel composition iscombusted in the engine than when the same fuel composition without thecombination of the hydrocarbyl-substituted aromatic compound and thepolyalkyleneamine is combusted in the engine.
 17. The method of claim16, wherein the hydrocarbyl-substituted aromatic compound is a MannichBase additive.
 18. The method of claim 16, wherein the polyalkyleneamine is a polyisobutylene amine.
 19. The method of claim 16, whereinthe hydrocarbyl-substituted aromatic compound is present in the fuelcomposition at a concentration of actives of from about 20 ppm to about300 ppm.
 20. The method of claim 16, wherein the hydrocarbyl substituentof the aromatic compound exhibits a number average molecular weight offrom about 700 to about
 1500. 21. The method of claim 16, wherein thehydrocarbyl substituent of the aromatic compound is or comprisespolyisobutylene.
 22. The method of claim 16, wherein the polyalkyleneamine is present in the fuel composition at a concentration of activesof from about 50 ppm to about 500 ppm.
 23. The method of claim 16,wherein the polyalkylene amine contains a polyalkylene group thatexhibits a number average molecular weight of from about 700 to about1500.
 24. The method of claim 16, wherein the weight ratio of actives ofthe polyalkylene amine: the hydrocarbyl-substituted aromatic compound inthe fuel composition is in the range of from about 5:1 to about 1:5. 25.The method of claim 16, wherein the engine is a spark-ignition internalcombustion engine.
 26. The method of claim 16, wherein the engine is acompression-ignition gasoline internal combustion engine.
 27. The methodof claim 16, wherein the at least one polyalkylene amine is present inthe fuel composition at a concentration of actives of from 100 ppm to500 ppm.
 28. The method of claim 16, wherein the at least onepolyalkylene amine is present in the fuel composition at a concentrationof actives of from 160 ppm to 500 ppm.
 29. The method of claim 16,wherein the at least one hydrocarbyl-substituted aromatic compound ispresent in the fuel composition at a concentration of actives of from 70ppm to 200 ppm.
 30. The method of claim 16, wherein the at least onehydrocarbyl-substituted aromatic compound is present in the fuelcomposition at a concentration of actives of from 70 ppm to 200 ppm; andthe at least one polyalkylene amine is present in the fuel compositionat a concentration of actives of from 160 ppm to 500 ppm.
 31. The methodof claim 16, wherein the hydrocarbyl-substituted aromatic compound is aMannich Base additive, and the polyalkylene amine is a polyisobutyleneamine.
 32. A method of reducing the sludge forming tendency of a fuelcomposition for use in a spark-ignition internal combustion engine or acompression-ignition gasoline internal combustion engine which methodcomprises incorporating into the fuel composition in one or more steps:a. a hydrocarbyl-substituted aromatic compound; and b. a polyalkyleneamine to produce a fuel composition which comprises said additives incombination and which on use in said engine produces less sludge thanthe sludge formed when using in said engine the fuel composition withoutsaid combination of additives.
 33. The method of claim 32, wherein thehydrocarbyl-substituted aromatic compound is a Mannich Base additive andthe polyalkylene amine is a polyisobutylene amine.
 34. The method ofclaim 32, wherein the hydrocarbyl-substituted aromatic compound ispresent in the fuel composition at a concentration of actives of fromabout 20 ppm to about 300 ppm, and the polyalkylene amine is present inthe fuel composition at a concentration of actives of from about 50 ppmto about 500 ppm.
 35. A method of maintaining oil pathways and/orlubrication in a spark-ignition internal combustion engine or acompression-ignition gasoline internal combustion engine which methodcomprises supplying to the engine a fuel composition which comprises acombination of: a. a hydrocarbyl-substituted aromatic compound; and b. apolyalkylene amine.